Tissue-specific effects of fenthion on glutathione metabolism modulated by NAC and BSO in Oreochromis niloticus

Abstract

Introduction: The present study was designed to understand the effects of organophosphate (OP) insecticide and avicide fenthion on cellular redox status and the role of reduced glutathione (GSH) on fenthion toxicity in the liver and kidney of Oreochromis niloticus as a model organism. N-acetylcysteine (NAC) and buthionine sulfoximine (BSO) were injected intraperitoneally to fenthion-exposed fish as modulators of GSH metabolism. GSH redox status, GSH-related enzyme activities, and thiobarbituric acid reactive substances (TBARS) contents were then measured spectrophotometrically at 24, 48, and 96 hours. To assess recovery from fenthion exposure, similar analyses were performed on fish transferred to non-treated water for 24, 48, and 96 hours.

Results: Fenthion increased glutathione S-transferase (GST; EC 2.5.1.18) activity and caused changes in total GSH (tGSH), GSH and oxidized glutathione (GSSG) contents and glutathione peroxidase (GPx; EC 1.11.1.9) specific activity in the liver tissue over time. Increases observed in tGSH and GSSG contents at 24 hours were decreased by fenthion treatment at 96 hours. BSO caused a sharp decline in liver tGSH, GSH, and GSSG contents and an elevation in GST and gamma-glutamyl transpeptidase (gamma-GT; EC 2.3.2.2) enzyme activities. A significant decrease was observed in tGSH and GSH contents and, also, GST enzyme activities in the kidney at 48-hour fenthion treatment. On the contrary to the liver, a significant increase was observed in tGSH and GSH contents in the kidney by BSO injection. NAC application eliminated the decreasing effects of fenthion on GST activity in this tissue. NAC injection caused decreases in lipid peroxidation (LPO) levels. Decline in tGSH and GSH contents were maintained in the liver during the recovery period, and elevations in LPO levels in the kidney were observed during the same period.

Conclusions: In conclusion, tissue-specific and time-dependent GSH redox status disturbance of fenthion were observed. BSO revealed the significance of GST-mediated GSH conjugation on the detoxification process of fenthion. NAC seemed useful to avoid the fenthion-related oxidative toxicity.